1. Field of the Invention
The present invention is directed to a respiratory and cardiac monitor for humans and other mammals. More specifically, the present invention is directed to a respiratory and cardiac monitor which takes advantage of the discovery that the electromagnetic permeability of the human body varies with the above-noted body functions.
2. Brief Description of the Prior Art
Respiratory monitors (apnea detectors) of the prior art operate on the principle that impedance of the human body (primarily of the trunk) changes during the respiratory cycle. A disadvantage of these prior art apnea detectors is that one or more electrodes of the monitor are attached to the skin. As is well known in the art, attached electrodes are less than perfectly tolerated by the human body, and can cause skin irritation, rash, eczema, and in some instances even skin ulcers. Dressing and undressing of patients who have electrodes attached to the skin can also be a problem.
Another serious disadvantage of apnea detectors which operate on the principle of detecting varying impedance of the human body is that their circuitry is highly susceptible to noise, particularly noise represented by high frequency electromagnetic and electrostatic radiation. Accordingly, there exists in the prior art a need for a respiratory monitor/apnea detector which does not require the use of electrodes and is significantly less susceptible to noise. The present invention provides such a respiratory monitor/apnea detector.